Baffle for tube assemblies



Feb. 19, 1952 E J. WEBER 2,586,408

BAFF LE FOR TUBE ASSEMBLIES Filed May 20, 1946 SUPPORT COLLARS FIG. 3

BAFFLE PLATE m fl m V2 COLLAR 2 INVENTOR; L. J. WEBER ATTORNEYS Patented Feb. 19, 1952 UNITED STATES PATENT OFFICE 2,586,408 BAFFLE FOR TUBE ASSEMBLIES Louis J. Weber, Bartlesville, Okla., assignor to Phillips Petroleum Company, a corporation of Delaware Application May '20, 1946, Serial No. 671,107

4 Claims. 1

This invention relates to baffles or dividing plates for use in tube assemblies. In one particular aspect it relates to an improved design of bafile plates and in another particular aspect it relates to an improved method -of installing 'a'nd supporting such baffie plates in a tube assembly.

Bafiie plates are "extensively used to control the path of hot gases passing over tube assemblies in catalyst cases, boilers, heaters and similar equipment. conventionally, 'bafilesfor such assemblies are made of heavy c'a'stin'gs or refractory materials. Such balile's are very heavy and require heavy beams for their support over long spans. Refractory bafiles must be formed or cast in place around tubes in an assembly and can be used only once; replacement with new material is necessary if the bafiie is removed to permit work on tu-bes. Cast ba-files are very difiicult to install and remove. Tube assemblies are also frequently subject to vibration, movement and expansion. With cast baflies or bailles formed in situ from refractory materials, it is not possible to have tight seals around the tubes of the assembly and still allow much freedom of tube movement.

In certain applications such as in catalyst cases of the sort described in the copending application of McCullough, Dolezal, Hays and Bachmuth. Serial No. 540,676, filed June 16, 1944. now abandoned, and the continuation-impart thereof Serial No. 762.314, filed July 21, 1947, extreme temperature variations and resulting tube eX- pansion and movement occur. In such installations variations in temperature of approximately l400 F. are sometimes encountered in a routine operation. Under such operating conditions, cast b'ailles and bafile's formed from refractory materials sag, fail, grow by deposit of oxidation prodnets. and bind, distort and break tubes of the assembly.

A lightweight, demountable bafile which is capable of automatically adjusting itself to compensate for eirpansion and tube movement while maintaining a substantially gas tight seal around tubes of an assembly is a "highly desirable and hitherto unknown improvement.

It is an object of this invention to provide a baffle for a tube assembly which may be supported by the tubes contained in said assembly.

A further object is to provide a bafile for a tube assembly which automatically adjusts itself to compensate for expansion and contraction of the battle and to compensate for tube movement due to expansion of tubes and headers of such tube assembly, while maintaining a substantially gas tight seal aro'u'd the tubes in said assem ly.

2 Another object is "to provide a balile for a tube assembly which may be easily and rapidly assembled and disassembled and which may be used repeatedly.

Another object is to provide a bafile which is simple, rugged and cheap in construction and which has the particular advantageous arrangemer t and combination of parts shown.

Other objects and advantages will become apparen to those skilled in the art as this disclosure proceeds.

I have found that an efiective baflle may be constructed by attaching collars to the tubes of such assembly and supporting a plurality of specially designed lightweight plates thereon in the manner hereinafter described.

Although myinvention is operative and applicable to any tube assembly requiring a baflle. it is especially useful in tube installations designed to be subjected to extreme variations in temperature, vibration, or movement of tubes due to eicpa'nsion and contraction of headers, etc., in which preservation of a substantially gas tight seal around the tubes is desirable.

Drawings In the accompanying drawings which show diagrammatically two particular embodiments of my invention, Fig. 1 shows a half collar in perspeeuve, Fig. 2 is a plan of one of the plates used in said embodiment, Fig. 3 is a side elevation of a tube assembly with baffle in place and is divided into two parts: A, showing one arrangement of plates. and B, showing a second arrangement; and Fig. 4 is a plan of tube assembly and bafile showing the same two arrangements of plates. Like reference numerals apply to like parts throughout the various figures of the drawings.

, Fig. 2 shows a plan of an individual plate ll used in forming my battle. Plate l l is flat and has cutoutindentations in its edges adapted to receive the tubes of ad acent rows of tubes in the assembly. The cutout indentations are adapted to fit loosely on and partially encircle said tubes and are ofsuflici'ent depth to permit the edges of plates l l to extend beyond the centerline of said tubes.

The complete bafiie is constructed as shown in Figs. 3A and 4A in whichtubes l2 are shown attached to cross headers l5 which are in turn attached to inlet header l3 and outlet header I4. A pair of half collars i0 is attached to each tube 12 of the assembly to form supporting collars having their flanges iying in the same plane at COilt height TOT supporting bane plat es. Section A of Figs. 3 and 4 shows a plurality of plates I I are then laid in alternate spaces between rows of tubes with cutout indentations in the edges of each plate partially encircling tubes of adjacent rows. Other similar plates are then laid in the alternate spaces between rows of tubes left vacant as a result of such placement of plates and are disposed with their edges overlapping and upported by the plates first installed, and complete the encirclement of each tube. Such placement results in a series of plates in which adjacent plates lie in different planes, namely an upper plane and a lower plane, with the edges of each plate overlapping the edges of adjacent plates, and in substantially gas tight contact therewith. Substantially gas tight joints are formed by contact of plates in said lower plane with a portion of a flange of each collar. That portion of each collar not overlaid by a plate in said lower plane is built up with insulating cement or refractory material, as shown in Fig. 3, to make contact with a plate in the upper plane. By disconnecting top and bottom cross headers and removing only three baiiie plates a complete section of tubes with a top and bottom cross header may be lifted out of the assembly for repair or replacement.

The modified arrangement of plates shown in sections B of Figs. 3 and 4 is especially useful where a as is passed over a baffle at high velocity. In this arrangement one edge of each plate rests upon collars attached to tubes of the assembly and the opposite edge of the plates rests upon an edge of the next plate. The plates thus are sloped up in the direction of gas flow and high velocity of ases passing over the baffie cannot raise a bafile plate from its seat, but on the other hand does exert a pressure on the plates tending to force them firmly down upon their supports.

The width of plates I l and the flanges of half collars l ma be varied as desired to give any degree of overl pping which may be necessary. I have found that a plate width sufiicient to give an overlap of about one inch at the edges is sufiicient for most installations. I have also found that a width of collar flange of about 1% inches is sufficient for providing support and maintaining substant llv gas tight seals under most operating conditions.

Plates I I may be formed of any material suitable for the temperatures encountered in use. Best results are received by the use of materials which do not grow by deposit of oxidation products at the temperatures expected to be encountered. For low temperature installations aluminum plates may be used; for temperatures up to about 1400" F. stainless steels, such as 12 chrome steel, may be used: and for temperatures from 1400 F. to 2000 F., 25 to 30 chrome stainless steels are desired. For very high temperatures the plates may be formed of light refractory blocks with their interstices filled with refractory cement.

Advantages This baffle has many advantages. The multiplicity of points of support effectively prevents the baflie plates from sagging and becoming deformed during operation, so that light weight plates may be used. Light weight plates may be formed from heat resistant alloys, such as stainless steels, as cheaply as conventional cast bafiies and do not require the heavy bracing necessary for the support of cast bailies. A particular advanta e resulting from the multiple support and lightweight features of this baiiie is that expensive alloys, such as stainless steels, may be ll-Sgq and thereb difliculties in operation due to growth of the bailie by deposit of oxidation products may be eliminated. Use of expensive alloys in baflies of conventional cast construction is usually not commercially feasible.

The half collars can be quickly and easily located on the tubes either in the fabricators shop or in the field. Welded to the tubes they become an integral part thereof and cooperate with refractory sealing material to maintain a substantially gas tight seal around the tube. Apertures in refractory baffies for the passage of tubes usually become enlarged and permit considerable passage of gas therethrough. Cast baffles are not manufactured to close tolerances and cannot fit tubes closely enough to prevent considerable gas leakage.

Bafiles constructed in accordance with my invention are not subject to damage by vibration, movement or expansion of the tubular elements of the assembly since the plates are not fastened to any part of the tubes and the indentations in the edges of the bafile plates fit the tubes loosely enough to permit the tubes to move. Such a bafile does not distort tubes. Refractory baflles are often cracked by vibration and movement of tubes. Cast bafiles often break tubes of an assembly b restricting their movement. My invention permits substantial movement of tubes in response to expansion of headers.

My invention provides a baflle which may be easily and quickly assembled. The plates of this bafile may be removed at any time when it becomes necessary to change tubes or dismantle the unit and they are not damaged by repeated insertions and removals, whereas conventional refractory bafiles can be used but once.

Cast or refractory bafiles are so heavy as to place undue strain on tubes when attempts are made to support such baflles by means of the tubes of an assembly. It is usually necessary to support such bafiles by heavy beams which restrict the movement of the bafiles. Support of such baflles by beams either leaves considerable areas of the bafiie unsupported with resulting tendency to sag and drop or increases the size of the installation bv necessitating an arrangement of tubes which will allow multiplicity of supporting beams. All such disadvantages are overcome by the use of my invention.

Example A large commercial butadiene plant is equip ed with '72 catalyst cases a proximately 10 x 15 feet. Within these cases 3% inch catalyst tubes are disposed as shown in Fig. 4 in rows approximately 9 inches apart, center-tocenterdistance. In routine operation these tubes are subjected to a temperature change of approximately 1400 F. at one point. Movement of tubes due to expansion of headers amounts to 1 to 1% inches during this operation. A baffle is required for directing heating and cooling gases in their path over these tubes.

Conventional commercial bafiles of a special grade of cast iron were installed. These baffles were unsatisfactory in service because of extensive breakage, sagging and growth at high temperatures. In a 10-foot length of this commercial baiiie, growth of the baffle by oxidation deposits was found to amount to as much as 3 inches in 9 months of use and tubes of the assembly were distorted by such accumulation of oxidation products. Expense of maintenance and replacement of these baffies amounted to more than $800 per month.

A number of such bafiles were replaced byothers constructed according to the principles of my invention. In these replacement baffles, plates having the plan shown in Fig. 2 were used. These plates were punched from -gauge steel of the grade sold as #410 AlSI Stainless and had an overall width of around 8 /2 inches, suflicient to give an overlap of about one inch at each edge. The supporting collars on each tube of the assembly had flanges about 1 /2 inches wide.

All baffie troubles have been overcome by the use of these bafiles. The remaining catalyst cases of this group are being equipped with bafiies constructed according to my invention as speedily as is practical.

Many obvious changes in construction may be made in this bafiie. For instance full collars may be used instead of the half collars shown. Full collars are particularly adapted for use in the fabricators plant, but lack the convenience of half collars in field use. It is to be understood that the forms of the invention, herewith shown and described, are to be taken as preferred examples of the same and obvious changes in shape, size and arrangement of parts may be made without departing from the spirit of the invention which is defined and solely limited by the subjoined claims.

I claim:

1. In a catalyst case comprising a series of rows of vertical catalyst tubes connected at their upper ends to an upper series of cross header tubes and at their lower ends to a lower series of cross header tubes so as to form two parallel spaced-apart rows of tubes connecting each pair of upper and lower headers, said upper series of cross header tubes being connected to a first conduit and said lower series of header tubes 6 being connected to a second conduit, said arrangement providing for flow of fluids through said catalyst tubes from one of said conduits to the other: a bafile assembly comprising collars fixed on each of said catalyst tubes in a common plane intermediate said headers; a series of flat plates slidably supported on said collars and extending across said case between adjacent rows of said catalyst tubes, said plates being notched to fit loosely around said catalyst tubes and slidably overlapped along their edges so as to form a continuous and gas-tight slidably-expansible bafile across said case, said structure avoiding stress on said tubes and on said plates upon expansion and contraction of the tube and bafile structure and permitting removal of a pair of rows of said tubes with their cross headers by removal of only the baflles adjacent said lastnamed tubes.

2. The apparatus defined by claim 1 in which alternate plates overlap their adjacent plates.

3. The apparatus defined by claim 1 in which each plate overlaps the next succeeding plate.

4. The apparatus defined by claim 1 in which said collars have a flange on the upper edge thereof to provide additional supporting surface for said plates.

LOUIS J. WEBER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 527,729 Sewell Oct. 16, 1894 1,231,896 Jacobus July 3, 1917 1,563,567 Harter Dec. 1, 1925 1,602,678 Kent Oct. 12, 1946 

